We keep our heavy bulk food (water, canned goods, etc) on what are generally heavy-duty shelves; 2’ deep, 5’ wide, 6’ tall. However, the shelves are 3/8" chipboard, and they sag a lot. We’ve been worried that they would break through.
I bought some heavy-duty channel strut:
After measuring the shelves, I cut sections 1’ 11 13/16" long, and then cut 3/8" off each end except for the top. I rough-cut with a saw and finished on the mill just because I have one, but if I didn’t, sawing and filing would have just taken a little longer. Here’s what one end looks like, partway through filing:
Even with a mill, I discovered that I really wanted to rough-cut with a saw; I stalled my mill hogging it out on the first attempt. After that, I used the horizontal band saw for the longer cuts, and a hacksaw to cut the tabs off:
I used a corncob mill for finishing. After rough-cutting with a saw, it was pretty quick work; the mill was short enough that I had to do two passes, but after the experiments on the first two braces I made, the last three took only about two minutes per end to cut, and maybe one more to file smooth.
Sadly, I forgot that I had to synchronize my cuts with the holes in the base of the strut at one point, so I have one piece that looks like this:
That one is installed under a lightly-loaded shelf.
Installed, they look like this:
I have one under the middle of most of the shelves, and two spaced roughly evenly beneath the most heavily-loaded shelf. It no longer appears that the shelves are about to snap, and we can use the space more efficiently now!
If I were doing this again, I would consider using the lighter weight channel strut. It appears that what I bought is overkill for the purpose to which I’m putting it, and the rolled edges extend about 1/4" below the bottom of the shelf supports.
The same thing could be done, of course, with rectangular tube, but this was cheaper when I bought it and gets the job done.